Unity Linux 20.1070a Security Update: kernel (UTSA-2026-146348)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(372549);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/27");

  script_cve_id("CVE-2026-74609");

  script_name(english:"Unity Linux 20.1070a Security Update: kernel (UTSA-2026-146348)");

  script_set_attribute(attribute:"synopsis", value:
"The Unity Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the
UTSA-2026-146348 advisory.

    In the Linux kernel, the following vulnerability has been resolved:

    tipc: read le->link under the node lock in tipc_node_link_down()

    tipc_node_link_down() caches the link pointer before taking n->lock:

            struct tipc_link *l = le->link;         /* unlocked */

            if (!l)
                    return;
            tipc_node_write_lock(n);
            if (!tipc_link_is_establishing(l)) {    /* deref l */
            ...
                    tipc_link_reset(l);             /* write into l */
            if (delete) {
                    kfree(l);
                    le->link = NULL;

    The delete=true caller frees that very object under n->lock, so the lock
    does not protect the cached pointer against it:

     - CPU A, delete=false: tipc_rcv() on TIPC_LINK_DOWN_EVT, or the link
       supervision timer via tipc_node_timeout(), reads l unlocked and then
       dereferences it under n->lock;
     - CPU B, delete=true: netlink TIPC_NL_BEARER_DISABLE -> bearer_disable()
       -> tipc_node_delete_links() -> tipc_node_link_down(n, bearer_id, true)
       -> kfree(l).

    The link is freed with plain kfree(), not kfree_rcu(), and for UDP bearers
    disable_media() only schedules the asynchronous cleanup_bearer() work, so
    its synchronize_net() runs after the links are already gone.  An in-flight
    CPU A that has read l therefore dereferences freed memory once B frees it:
    a use-after-free read in tipc_link_is_establishing(), and a use-after-free
    write via tipc_link_reset() on the establishing branch.

    The following trace was captured on 7.2.0-rc5-00284-gaf39eb111ce6:

      BUG: KASAN: slab-use-after-free in tipc_link_is_establishing (net/tipc/link.c:285)
      Read of size 4 at addr ffff88802e2aa068 by task swapper/2/0
       tipc_link_is_establishing (net/tipc/link.c:285)
       tipc_node_link_down (net/tipc/node.c:1076)
       tipc_node_timeout (net/tipc/node.c:843)
      Allocated by task 9549:
       tipc_link_create (net/tipc/link.c:490)
       tipc_node_check_dest (net/tipc/node.c:1279)
       tipc_disc_rcv (net/tipc/discover.c:252)
       tipc_udp_recv (net/tipc/udp_media.c:389)
      Freed by task 9549:
       tipc_node_link_down (net/tipc/node.c:1084)
       tipc_node_delete_links (net/tipc/node.c:1320)
       bearer_disable (net/tipc/bearer.c:414)
       __tipc_nl_bearer_disable (net/tipc/bearer.c:992)

    Move the le->link read inside tipc_node_write_lock(), so it is serialised
    against the kfree() in the delete path.  A racing teardown now either has
    not run yet, and we see a valid link, or has already run, and we see NULL.

Tenable has extracted the preceding description block directly from the Unity Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  # https://src.uniontech.com/#/security_advisory_detail?utsa_id=UTSA-2026-146348
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?a626d32e");
  # https://lore.kernel.org/linux-cve-announce/2026082217-CVE-2026-74609-e7db@gregkh
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?7ddac1d1");
  script_set_attribute(attribute:"see_also", value:"https://nvd.nist.gov/vuln/detail/CVE-2026-74609");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:S/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-74609");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/08/22");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/10/28");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/27");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Unity Linux Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info2.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/UOS-Server/release", "Host/UOS-Server/rpm-list", "Host/cpu");

  exit(0);
}
include('rpm2.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_product = get_kb_item('installed_os/local/SSH/0/product');
if (isnull(os_product) || 'UOS Server' >!< os_product) audit(AUDIT_OS_NOT, 'UOS Server');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'UOS Server');
if (! preg(pattern:"^(20.1070a)([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'UOS Server 20.1070a', 'UOS Server ' + os_version);

if (!get_kb_item('Host/UOS-Server/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('aarch64' >!< cpu && 'amd64' >!< cpu && 'loongarch64' >!< cpu && 'x86_64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'UOS Server', cpu);


var constraints = [
  {
    'release': '20',
    'sp': '1070a',
    'pkgs': [
      {'reference':'kernel-4.19.0-91.82.190.028.uelc20', 'sp':'1070a', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.0-91.82.190.028.uelc20', 'sp':'1070a', 'cpu':'amd64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.0-91.82.190.028.uelc20', 'sp':'1070a', 'cpu':'loongarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'kernel-4.19.0-91.82.190.028.uelc20', 'sp':'1070a', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

var os_release = get_one_kb_item('installed_os/local/SSH/0/release');
var os_sp = get_one_kb_item('Host/*/minor_release');

var flag = 0;
var reference;
var sp;
var _cpu;
var el_string;
var rpm_spec_vers_cmp;
var epoch;
var allowmaj;
var exists_check;
var cves;
foreach var constraint ( constraints ) {
  # Check that the target release is equal to the affected release
  if (!empty_or_null(constraint['release'])){
    if (constraint['release'] != os_release) continue;
  }
  if (!empty_or_null(constraint['sp'])){
    if (constraint['sp'] != os_sp) continue;
  }
  foreach var pkg ( constraint['pkgs'] ) {
    reference = NULL;
    sp = NULL;
    _cpu = NULL;
    el_string = NULL;
    rpm_spec_vers_cmp = NULL;
    epoch = NULL;
    allowmaj = NULL;
    exists_check = NULL;
    cves = NULL;
    if (!empty_or_null(pkg['reference'])) reference = pkg['reference'];
    if (!empty_or_null(pkg['sp'])) sp = pkg['sp'];
    if (!empty_or_null(pkg['cpu'])) _cpu = pkg['cpu'];
    if (!empty_or_null(pkg['el_string'])) el_string = pkg['el_string'];
    if (!empty_or_null(pkg['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = pkg['rpm_spec_vers_cmp'];
    if (!empty_or_null(pkg['epoch'])) epoch = pkg['epoch'];
    if (!empty_or_null(pkg['allowmaj'])) allowmaj = pkg['allowmaj'];
    if (!empty_or_null(pkg['exists_check'])) exists_check = pkg['exists_check'];
    if (!empty_or_null(pkg['cves'])) cves = pkg['cves'];
    if (reference &&
        ## (no known rpm to check OR known rpm_exists)
        (!exists_check || rpm_exists(rpm:exists_check)) &&
        rpm_check(sp:sp, cpu:_cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj, cves:cves)) flag++;
  }
}


if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'kernel');
}